It is proved in [1]} that \(k\) th–norms of the characteristic function of any set are connected to each other.
It is shown in [2]} that the connection for the non-normalised norms does not depend on size of the group \(G\) .
Here we formulate a particular case of [2]},
which relates \(\Vert  {\mathcal {A}}\Vert _{\mathcal {U}^{k}}\)  and \(\Vert  {\mathcal {A}}\Vert _{\mathcal {U}^{2}}\) .
